The present invention relates generally to an improved shock absorber arrangement, and more specifically to a shock absorber that coordinates valving in a cylinder assembly with valving in a piston assembly and has a cylinder assembly which includes an extruded reservoir housing and a pressed in sleeve.
Standard shock absorbers are currently controlled by high velocity control valves and low velocity valve ports disposed in the piston. The low velocity valve ports are simply holes through the piston with the degree of control being determined by the size and number of the holes in the piston. High velocity control is accomplished by holes in the piston being con trolled by spring washers. When velocity of fluid in front of the piston increases to a point where the fluid can not pass through the low velocity ports at a sufficient rate pressure will build to a point where the pressure exerted by the spring washers is overcome and they are forced to open thereby permitting fluid to pass through the high velocity control valves. The amount of tension in the spring washers determines the amount of restriction to the high velocity flow and thus how much energy is absorbed. To change the energy absorption rate of standard shock absorbers requires a change in the size and/or the number of the ports in the piston and a change in the size and/or the number of spring washers used.
The most significant problem with standard shock absorbers is that they only sense velocity no matter how far the piston has moved within the shock absorber. Therefore, a small bump hit at high speed will create a velocity which will cause the shock absorber to use the high speed control valves thereby resulting in a harsh ride for the user even though the terrain is generally level except for small bumps. This situation can not be corrected by simply enlarging the low velocity control ports because if too much fluid is permitted to pass through the low velocity ports there will not be enough left to keep the shock absorber from bottoming out, e.g., when the shock absorber responds to a small bump immediately followed by a much larger bump.
Shock absorbers are generally well known and various approaches have been taken to improve the manner in which they operate as well as the ease with which they are manufactured. An early tube-type shock absorber, U.S. Pat. No. 1,571,788, shows the use of external compartments with valves therebetween for controlling fluid flow from one side of the piston to the other. Another shock absorber, U.S. Pat. No. 2,360,755, teaches two stage shock absorption and includes a surrounding reserve chamber. U.S. Pat. No. 3,213,973 teaches the concept of one tube within another tube wherein the inner tube has two sets of ports and separate passageways for each set of ports. Yet another shock absorber, U.S. Pat. No. 2,410,176, incorporates an end cap with a valve for pressurizing the shock. U.S. Pat. No. 3,226,103 shows a shock absorber having an inflatable bladder and a fluid chamber surrounding a tubular member containing the piston assembly. Another shock absorber with an inflatable bladder is shown in U.S. Pat. No. 4,700,815.
None of the shock absorbers currently available in the market or found in the prior art patents approaches the invention as disclosed and claimed herein.